The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Internal combustion engines combust an air and fuel mixture within cylinders to drive pistons, which produces drive torque. Air flow into gasoline engines is regulated via a throttle. More specifically, the throttle adjusts throttle area, which increases or decreases air flow into the engine. As the throttle area increases, the air flow into the engine increases. A fuel control system adjusts the rate that fuel is injected to provide a desired air/fuel mixture to the cylinders. Increasing the amount of air and fuel provided to the cylinders increases the torque output of the engine.
Engine control systems have been developed to control engine torque output to achieve a desired torque. Traditional engine control systems, however, do not control the engine torque output as accurately as desired. Further, traditional engine control systems do not provide a rapid response to control signals or coordinate engine torque control among various devices that affect the engine torque output.
Moving the vehicle from zero velocity to a desired velocity is referred to as a launch. Making the launch smooth “feeling” to the driver is important. Obtaining the smooth feeling is related to the power provided by the engine. The power should rise at an acceptable rate and not overshoot and then come back down. When overshoot occurs the vehicle response is non-linear and lurches followed by lagging feeling.
If the power rises too slowly the vehicle will feel sluggish. If the power rises too fast then the driver may be uncomfortable. Obtaining a smooth launch feeling is easily delivered in an accelerator pedal-to-throttle mapped system. Obtaining a smooth feeling in a system where the throttle and other airflow actuators are controlled by a torque request is difficult with gasoline engines because of manifold and cylinder filling response to times an air actuator change. The manifold has some delay associated with obtaining the desired power when requested. Furthermore the hydrodynamic torque converter in automatic transmissions can provide transient control issues because of the rapid engine speed change on launch.